1. Field of the Invention
The invention relates to the training, evaluation, and retraining of factors that limit human performance. Specifically, the invention relates to a method and apparatus for training, evaluating and reconditioning the performance of the arm, shoulder, and legs.
2. Description of the Related Art
Rehabilitation specialists are often asked to conduct an assessment of patients that have acquired a limitation to their optimal independent activity. Reconditioning or retraining of functional human performance is also an important goal of rehabilitation.
Although the parameters of human performance vary widely, one may identify several principles which are common to all forms of independent activity. Such common principles are muscular strength, endurance, joint range of motion, and motor coordination. It is these parameters of performance that the rehabilitation specialist will focus upon. The specialist directs attention upon the identified parameter's which are limiting performance and evaluates the degree of the limitation.
In the process of reconditioning, each of these principles will also be the focus of attention. Each of them will be enhanced by retraining therapy. The underlying physiological adaptations responsible for performance enhancement include, but are not limited to, vascularity, cell biochemistry and motor coordination skills.
The methods used in both the assessment and retraining process of the muscle groups are closely related. Both procedures physically tax or overload the affected muscle group to quantify its performance and also to cause biological adaptations to improve the performance of that muscle group. Historically, the rehabilitation specialist will have a hands on approach using his own healthy limb to resist the movement of the patient's limb. In this way, the clinician evaluates the patient's performance through feel and, at the same time, offers exercise to the limited muscle group. By repetitive, hands on, accommodating exercise, the limited muscle group is overloaded and adapts biologically with improved performance.
For example, muscle strength is a performance parameter which is quite plastic in quickly adapting to immobilization or disuse as well as to increased activity or overuse. That is, muscle strength quite quickly increases or decreases with respect to use or disuse. Disuse, such as immobilization following injury or casting after surgery, results in a significant decrement in muscle size and hence muscle strength. In contrast, if free weight lifting is used as the method of choice for the rehabilitation therapy, the end result is a quick response of increased muscle cell size and hence gains in muscle strength.
Weight lifting equipment will overload a muscle group by using gravity against which a muscle must move the weight. With free weights, no controls are present to direct the speed of movement of the limb nor the resistance throughout the range of motion that the muscle must work against. The maximum free weight resistive load that can be applied to a limb is determined by the capacity of the associated muscle group as measured throughout the range of motion of the limb. The maximum load that the limb can support varies throughout its range of motion where at some point it is at a minimum and at another it is at a maximum. Hence, the maximum resistive free weight load that can be applied is equal to the maximum supportable load in the weakest area of the range of motion.
Conventional methods of subjective assessment and reconditioning, such as subjective "through the clinician's hands" evaluations and free weight exercise, are now reinforced with technology.
Technology has been developed which provides for assessment and reconditioning of muscular deficiencies by electronic control of the rate of movement of the limb. This rate of movement control is achieved by constantly varying the amount of resistance offered the moving limb throughout the range of motion. This category of devices are to allow the muscle group, usually a whole limb or limb segment, to accelerate to a pre-selected speed. These constant speed devices use the methods of isokinetic or accommodating resistance.
In the isokinetic system, once the moving limb achieves the selected speed, the device then offers the muscle group an accommodating resistance which is proportional to the contractile force such that the limb continues to move at the selected speed. These mechanisms usually have some form of position/time feed back, servo loop which directs the resistance, for example, through feeding a variable current to a DC servo motor, to be such that, no matter what constantly varying force is executed by the contracting muscle group, the limb does not exceed or fall below the speed selected.
The goal with isokinetic systems is that throughout the entire range of motion of the limb, the associated muscle groups are working at their utmost level while receiving an optimal overloading resistance.
The contractile effort of a muscle group against this type of microprocessor based resistance is registered by the system and produces a profile of contractile performance which is widely recognized as accurate and repeatable. The data from such a system can be used in a court of law as evidence in disability claims.
Examples of such isokinetic systems are the Cybex, manufactured by Lumex, U.S. Pat. No. 3,465,592, inventor J. Perrine; the LIDO manufactured by Loredan, U.S. Pat. No. 4,601,468; inventor M. Bond, KIN COM manufactured by Chattanooga, U.S. Pat. No. 4,711,450, inventor J. McArther; the Biodex, U.S. Pat. No. 4,628,910, inventor R. Krukowski and U.S. Pat. No. 4,691,694, inventor R. Boyd, et al.; and the devices disclosed in U.S. Pat. Nos. 3,848,467 and 4,235,437. Each of these systems use the method of isokinetic resistive exercise/assessment applied to the large muscle groups of the legs particularly the knee. Attachments are also available to modify some of these devices to address the arms and, secondarily, the ankle, wrist and hand.
These systems represent an application of the "open chain" concept of evaluation and training. That is, the particular joint or muscle group under test is isolated and subjected to testing, evaluation and/or training while the balance of the limb or body is restrained in a fixed position. Recent studies have indicated that such systems are not as accurate a reflection of the work patterns of the muscular system as originally thought {CITE?}. A preferred system of limb training and evaluation involves allowing the entire limb to move throughout its normal functional course, thereby integrating the action of all muscular groups involved in the moving the limb in a more realistic manner. Such a system provides a more accurate representation of the status of the particular muscle group or joint range under test.
To date, no such "closed chain" systems are available which provide adaptability to different limbs and incorporate the ability to analyze the forces present on individual muscle groups or joints of a particular limb, and the ability to utilize various resistance modes for testing and training.
For example, a system known as the Kinetron, manufactured by Cybex Corporation, [address], is a passive, hydraulic based closed chain system. The system utilizes a full weight bearing approach wherein the hydraulic resistance responds to the full weight of the test subject, supported by the subject's leg. The Kinetron does not provide various resistance modes and, in particular, lacks the ability to discern the forces present on individual muscle groups or joints during the test exercise.
Another example of the currently available closed chain system is the Nova MLE, manufactured by Nova Biodesign, Inc., and disclosed in U.S. Pat. No. 4,679,786. In this system, a user can exercise by engaging four slides, one for each limb. The slides travel along parallel paths, enabling reciprocating motion, although the slides are not required to function in reciprocating fashion. Each slide connects to a chain or cable segment, to enable reciprocating cable motion, which connect to gears, causing reciprocation of clutches, thereby impulsing a fly wheel in a single direction and causing rotation. Ostensibly, the system includes an electromagnetic brake which provides programmable loads from 5-100 lbs, with resistance controlled to match the strength curves of the user. Although the NOVA MLE may be preset with exercise programs tailored to the individual, the system does not provide complete analysis of the loads present on the individual joint systems of the limb under test. Neither does the apparatus provide various testing modes, such as isokinetic, isotonic or isometric resistance testing for the particular limbs under test.